Abstract. This paper presents the aerodynamic modelling and analysis of surfaces created by a novel deployable mechanism, which is composed of a four-bar linkage and a scissor-structural mechanism (SSM) which contains several scissor-like elements (SLEs). With the help of that mechanism, which is located inside the trailing portion of wing section, continuous adjustment of the airfoil is possible. In order to highlight the advantageous aerodynamic characteristics of newly created airfoil geometries via proposed SSM, several aerodynamic analyses have been performed. The flow characteristics used for the analyses are determined by the flight envelope of an intended generic UAV. Since the maximum speed range of the sample aircraft is well below Mach 0.3, incompressible flow assumption is made throughout the solutions and conservation laws of Reynolds Transport Theorem are employed.
Abstract. In this paper, design of a novel deployable scissor-structural mechanism (SSM) for active camber and chord morphing airfoil has been presented. The mechanism is created via combination of one four-bar linkage and various scissor-like elements (SLEs). The theory behind scissor-like elements and hierarchical design procedure are adequately explained. Following that design procedure, a scissor-structural mechanism is created in order to satisfy the desired airfoil shapes, which have different camber lines with minimum structural error. It is also possible to modify the chord length by changing the properties and types of the used SLEs. Modifying the design parameters of used SLEs, without increasing the degree-of-freedom (DOF) of the mechanism, will result in infinite number of results. With the help of error definition and developed computerroutine, the best scissor-structural mechanism which satisfy the required tasks properly can be detected.
In the design and analysis of morphing wings, several sciences need to be integrated. This article tries to answer the question, “What is the most appropriate actuation mechanism to morph the wing profile?” by introducing the synthesis, analysis, and design of a novel scissor-structural mechanism (SSM) for the trailing edge of a morphing wing. The SSM, which is deployable, is created via a combination of various scissor-like elements (SLEs). In order to provide mobility requirements, a four-bar linkage (FBL) is assembled with the proposed SSM. The SSM is designed with a novel kinematic synthesis concept, so it follows the airfoil camber with minimum design error. In this concept, assuming a fully-compliant wing skin, various types of SLEs are assembled together, and emergent SSM provide the desired airfoil geometries. In order to provide the required aerodynamic efficiency of newly-created airfoil geometries and obtain pressure distribution over the airfoil, two-dimensional (2D) aerodynamic analyses have been conducted. The analyses show similar aerodynamic behavior with the desired NACA airfoils. By assigning the approximate link masses and mass centers, the dynamic force analysis of the mechanism has also been performed, and the required torque to drive the newly-developed SSM is estimated as feasible.
In this paper, the dynamic force analysis of a novel deployable mechanism, called as scissor-structural mechanism (SSM), for active camber and chord morphing have been presented. The mechanism is created via combination of several scissor-like-elements (SLEs). With a novel kinematic synthesis concept, various types of scissor-like-elements are assembled together to provide the desired airfoil geometries. The types (translational, polar), the number of scissor-like-elements, their orientations with respect to centerline of the airfoil and their distribution frequencies over the chord length are the design parameters, which allow designers to achieve all the possible geometric shapes. With the assumption of an existing fullycompliant wing skin, it is possible to adjust the wing profile to various desired airfoil geometries. With the help of developed computer routine, the mechanism is generated which yields the minimum possible design error. After the selection of mechanism, the position, velocity and acceleration analyses of the mechanism have been done. In order to prove aerodynamic efficiency of newly created airfoil geometries and obtain pressure distribution over the airfoil, 2D aerodynamic analyses have been done with the package program XFOIL. The flow characteristics used for the analysis are determined by the flight envelope of a generic UAV. Obtained pressure distribution is applied as the lumped force on the joints. By assigning the approximate link masses and mass centers, the dynamic force analysis of the mechanism has also been performed in order to estimate the required torque to drive the synthesized mechanism.
In the field of missile and rocket design, efficiency is a crucial aspect considering factors such as weight, storage, stealth, and cost. Wraparound fins (WAFs) have been used for many years to control the trajectory of missiles and rockets because of their compactness and effectiveness. However, WAFs are structurally more flexible than other types of fins, which may negatively impact their dynamic behavior and aeroelastic response. This can cause catastrophic instabilities, such as flutter. To mitigate these challenges, it is essential to consider both aerodynamic and structural models of WAFs during the design process. In this study, the flutter velocity and frequency of WAFs were investigated in relation to different structural design configurations and sweep angles, in order to understand and improve the aeroelastic performance of swept WAFs.
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